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Abstract: Although rats are incapable of vomiting, they demonstrate profound avoidance of a flavor previously paired with an emetic drug. They also display conditioned gaping reactions during re-exposure to the flavor. This robust learning occurs in a single trial and with long delays (hours) between consumption of a novel flavor and the emetic treatment. However, conditioned flavor avoidance learning is not a selective measure of the emetic properties of drugs, because non-emetic treatments (even highly rewarding treatments) produce conditioned avoidance, and anti-emetic treatments are generally ineffective in suppressing conditioned avoidance produced by an emetic drug. On the other hand, conditioned gaping reactions are consistently produced by emetic drugs and are prevented by anti-emetic drugs, indicating that they may be a more selective measure of conditioned malaise in rats. Here we review the literature on the use of conditioned flavor avoidance and conditioned gaping reactions as rat measures of conditioned nausea, as well as the neuropharmacology and neuroanatomy of conditioned gaping reactions in rats. [Copyright &y& Elsevier]

Abstract: The effects of intra-accumbal infusion of selective agonists for the β-adrenoceptor subtypes on the noradrenaline and dopamine efflux in the nucleus accumbens of freely moving rats were investigated, using in vivo microdialysis. Neither β1-(dobutamine: 0.06 and 0.12pmol) nor β2-adrenoceptor agonist (salbutamol: 0.36 and 3.6pmol) altered the basal noradrenaline and dopamine efflux in the nucleus accumbens. Co-administration of 0.06pmol of dobutamine with salbutamol (3.6pmol) did not affect the noradrenaline levels, but it increased the dopamine efflux to approximately 120%. Co-administration of 0.12pmol of dobutamine with salbutamol (0.36 or 3.6pmol) also increased DA efflux to approximately 120% without affecting noradrenaline levels. The non-selective β-adrenoceptor antagonist l-propranolol (1200pmol) that did not alter the basal noradrenaline and dopamine levels, suppressed the dopamine efflux, induced by co-administration of dobutamine (0.12pmol) and salbutamol (3.6pmol). The doses mentioned are the total amount of drug over the 60-min infusion period. The present results support our previously reported conclusion that stimulation of accumbal β-adrenoceptors which are suggested to be postsynaptically located on accumbal dopaminergic terminals, can enhance the dopamine efflux in the nucleus accumbens. The present study also provides in vivo neurochemical evidence that concomitant, but not separate, activation of accumbal β1- and β2-adrenoceptors synergistically increases the accumbal dopamine efflux. [Copyright &y& Elsevier]

Abstract: Ghrelin is an endogenous peptide potentially useful in therapy of anorexia and other age-related metabolic disturbances. We evaluated the influence of age on the orexigenic and lipid metabolism-altering effects of ghrelin. Peripubertal, young, adult and middle-aged rats (1, 2, 7 and 12 months old, respectively) were treated with 5 daily intracerebroventricular injections of ghrelin (0.15nmol) or saline (control). The food intake was measured daily before treatment, while white adipose tissue and serum/plasma samples for detection of lipid metabolites/hormones were collected at the end of the experiment. The values of cumulative food intake and body weight gain declined, while the white adipose tissue deposits and blood concentrations of triglycerides, cholesterol and free fatty acids all increased with age. Ghrelin significantly increased all parameters, but the stimulatory effects on body weight gain and food intake were more pronounced in peripubertal/young rats, while the increase in white adipose mass, triglyceride and low-density lipoprotein cholesterol levels was more noticeable in adult/middle-aged animals. The decrease in sensitivity to ghrelin-mediated stimulation of food intake in older animals could not be explained by alterations in ghrelin's ability to reduce anorexigenic hormones insulin and leptin. However, the higher responsiveness of aged rats to ghrelin-mediated increase in lipid metabolites was accompanied by an increase in adrenocorticotropic hormone and corticosterone levels. These results indicate that aging, while reducing sensitivity to ghrelin-mediated increase in body weight gain and food intake, might enhance the responsiveness to the stimulatory effects of ghrelin on lipid metabolites and hypothalamic-pituitary-adrenal axis activity. [Copyright &y& Elsevier]

Abstract: Sirolimus is an immunosupressive drug that specifically inhibit the activation of T-lymphocytes. This study was undertaken to investigate whether treatment with sirolimus exert analgesic effect in rat adjuvant-induced arthritis, an animal model of rheumatoid arthritis. Arthritis was induced by a single subcutaneous injection of Freund's complete adjuvant to male Wistar rats that were divided into four groups; control (saline), vehicle (ethanol), sirolimus 0.75 and sirolimus 1.5. Sirolimus (0.75 and 1.5mg/kg/day) was administered intraperitoneally using Monday–Wednesday–Friday dosing schedule for 29 days, this dosing regimen revealed acceptable trough blood concentrations in arthritic rats. Adjuvant inoculation resulted in paw inflammation, hyperalgesia and allodynia as assessed by pletismometer, analgesymeter and dynamic plantar aesthesiometer respectively. Light microscopic evaluation of the arthritic metacarpophalangeal joints revealed synovial hypertrophy with inflammatory cellular infiltration, cartilage destruction and partial subchondral bone resorption. ELISA tests of serum TNF-α, IL-1β or IL-6 did not show any change in arthritic rats, while Western blotting analysis revealed a significant increase in TNF-α (P<0.001), but not IL-1β or IL-6, protein expression in the lumbar spinal cord of arthritic rats. Treatment with sirolimus significantly decreased the arthritic lesions (P<0.001) and paw swelling (P<0.05), alleviated the histological features in the metacarpophalangeal joint, resulted in antihyperalgesic and antiallodynic effects without affecting the locomotor activity and prevented the increased spinal cord TNF-α level (P<0.05). It seems that prevention of the increased TNF-α expression in the spinal cord may partially contribute to the antihyperalgesic effect of sirolimus in adjuvant arthritic rats and sirolimus could be a promising immunosupressive agent in the treatment of arthritic pain. [Copyright &y& Elsevier]

Abstract: Menthol, a naturally occurring compound in mint, is known to give cold sensation. However, previous findings about its pharmacological activity in blood vessels are full of paradox. The present study investigated the action of menthol on vascular reactivity in different arteries isolated from male Sprague–Dawley rats, e.g. aortae, main mesenteric arteries and coronary arteries. The arterial segments were suspended in organ bath or in wire myograph for measurement of isometric force. Menthol concentration-dependently relaxed all three arteries with similar relaxing sensitivity in arteries contracted by different contractors, KCl, U46619 (9,11-dideoxy-9α,11α-methanoepoxy Prostaglandin F2α) and phenylephrine. Menthol-induced relaxations were unaffected by nitric oxide synthase inhibitor L-NAME, soluble guanylyl cyclase inhibitor ODQ, or mechanical removal of endothelium. Menthol also concentration-dependently suppressed 60mM KCl-induced constriction and CaCl2-induced contraction in Ca2+-free K+-containing solution. Calcium fluorescent imaging using fluo-4 showed that 10min-incubation with 1mM menthol inhibited 60mM KCl-induced Ca2+ influx in rat aortic smooth muscle cell line A7r5 and vascular smooth muscle of coronary arteries. To conclude, menthol induces relaxation and inhibits contraction in rat aortae, mesenteric and coronary arteries primarily through inhibiting Ca2+ influx via nifedipine-sensitive Ca2+ channels in vascular smooth muscle. [Copyright &y& Elsevier]

Abstract: We examined the chemical specificity of benzoic (benzene–carboxylic) acid and its derivatives in increasing osmotic fragility (OF) in rat red blood cells (RBCs) in vitro. Benzoic acid increased the OF in the rat RBCs in a dose-dependent manner. Replacement of the carboxylic group with a phosphoric group also increased the OF in RBCs, whereas substitution of the carboxylic group by a sulfonic, amide or hydroxy group did not affect the OF. Replacement of the benzene nucleus with a cyclohexane ring or a straight hydrocarbon chain with six carbons resulted in a greater increase in OF than that induced by benzoic acid. Introduction of a methyl group, chloride or bromide at the m- and p-positions of the benzene ring considerably enhanced the increase in OF induced by benzoic acid. Substitution of the amino and hydroxy group at the m- and p- positions abolished the increase in OF induced by benzoic acid. The introduction of these elements at the o-position showed an almost equal increase in OF as that observed for benzoic acid. A molecule of benzoic acid is composed of both hydrophilic (carboxylic group) and hydrophobic (benzene ring) components. Replacement of the hydrophilic component changed the balance formed between hydrophobic and hydrophilic components in the moiety, resulting alterations to its interaction with the RBC membrane. The size, form and elements introduced into the benzene ring also affected its affinity to the cell membrane, and changed the osmotic resistance in rat RBCs. [Copyright &y& Elsevier]

Abstract: Not much has been reported about the effects of hyperthyroidism and its correction on resistance vessels, and just two inconsistent studies have investigated the impacts of restored euthyroidism on vascular reactivity. In this regard, we designed the current study to evaluate the vascular reactivity of the mesenteric arteries of hyperthyroid and restore euthyroid rats. Hyperthyroidism was induced by administration of triiodothyronine (T3; 300μg/kg, i.p., for 12 weeks in T3 group). Euthyroidism was restored by administration of T3 for 8 weeks and then T3+Methimazole (0.003% in drinking water) for 4 weeks (T3+MMI group). According to the McGregor method, vascular relaxation and contractility response were measured in response to acetylcholine or phenylephrine respectively. We found that maximal contractility response (E max ) to phenylephrine in the T3 group was significantly decreased (P<0.001), and E max to acetylcholine was significantly increased compared with the saline group (P<0.05). When NG-nitro-L-arginine methyl ester (L-NAME, 3×10−4 M) was used, E max to acetylcholine in the T3 group was still higher than the saline group (P<0.05). However, decrease in maximal response of the T3 group was significantly greater than the saline group (P<0.01). We also showed that when euthyroidism is restored by methimazole therapy, enhanced acetylcholine-induced vasorelaxation and impaired contractility response to phenylephrine were normalized, as there was no significant difference in E max of the T3+MMI group versus the saline group (P>0.05). In conclusion, synthesis of both nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) in mesenteric arteries significantly increased as a consequence of hyperthyroidism, and this abnormal vascular reactivity is corrected by methimazole therapy. [Copyright &y& Elsevier]

Abstract: Benzylquinolone carboxylic acid (BQCA) is a recently described cholinergic muscarinic M1 receptor positive allosteric modulator having potential as cognitive enhancer in dementia. The present study focused on the characterisation of BQCA’s mode of action in relation to positive effects on memory and side-effects in an animal model. To get insight into this mode of action, in vitro receptor potency/left shift experiments in cells stably expressing the rat’s M1 receptor were performed. They revealed an inflection point value of BQCA corresponding to 306nM, and potentiation of the agonist response up to 47-fold in presence of 10μM of BQCA. In vivo, brain microdialysis showed a maximal brain level of 270nM, 40min after i.p. administration at 10mg/kg. Based on in vitro data obtained with this dose, it can be concluded that BQCA reaches brain levels which should potentiate the agonist response about 4-fold. Behavioural data confirmed that BQCA used at 10mg/kg attenuated scopolamine-induced memory deficit in a spontaneous alternation task. Moreover, BQCA showed no side effect at 10mg/kg and above in spontaneous locomotion and salivation tests. The profile of BQCA observed in the present study displays a clear advantage over the M1–M3 agonist cevimeline. The present data show the therapeutic potential of the M1 receptor positive allosteric modulator BQCA for the treatment of memory deficits observed in Alzheimer’s disease. [Copyright &y& Elsevier]

Abstract: Endogenous hydrogen sulfide is produced by cystathionine-γ-lyase and cystathionine-β-synthase in a variety of tissues and has recently been implicated in the regulation of cardiac functions. Acceleration of the heart rate in response to catecholamines is impaired in patients with cirrhosis. The present study was aimed to examine the role of endogenous hydrogen sulfide in the pathogenesis of chronotropic dysfunction in rats with cirrhosis. Cirrhosis was induced by surgical ligation of bile duct in rats. There was no significant difference in atrial cystathionine-γ-lyase and cystathionine-β-synthase mRNA levels in control and cirrhotic rats as assessed by quantitative RT-PCR. Four weeks after bile duct ligation or sham surgery the atria were isolated and chronotropic responsiveness to adrenergic stimulation was assessed using standard organ bath. Incubation of the atria with propargylglycine (PAG, a cystathionine-γ-lyase inhibitor) and amino-oxyacetic acid (AOAA, a cystathionine-β-synthase inhibitor) was associated with a significant desensitization of chronotropic response to adrenergic stimulation in controls rats. This indicates that endogenous hydrogen sulfide might be involved in modulation of adrenergic signaling in the atrium. Bile duct ligation was associated with impaired chronotropic responsiveness to adrenergic stimulation in comparison with sham-operated rats. In contrast to control group, incubation of the atria with PAG and AOAA was able to partially improve the chronotropic responsiveness to adrenergic stimulation in cirrhotic rats. Our data shows that local inhibition of endogenous hydrogen sulfide in atria has opposite effect in cirrhotic versus control rats and may play a role in physiological modulation of adrenergic signaling in the atrium. [Copyright &y& Elsevier]

Abstract: Essential tremor (ET) is one of the most common and most disabling movement disorders among adults. The drug treatment of essential tremor remains unsatisfactory. Additional therapies are required for patients with inadequate response or intolerable side effects. Thus, we aimed to investigate the therapeutic effects of riluzole on harmaline-induced tremor and ataxia in rat, and determining whether riluzole exerts its effect through modulation of glutamate levels in cerebellum. The study included 5 groups of Wistar rats weighing 80–100g, injected with harmaline (50mg/kg i.p.) for inducing experimental tremors and ataxia. The rats in group 1 served as control (saline induced) and group 2 received harmaline alone, whereas the animals in groups 3, 4 and 5, were also given riluzole intraperitoneally at doses of 2, 4 and 8mg/kg 10min after harmaline administration, respectively. The intensity and duration of tremor were recorded. Rotarod test, distance traveled and number of crossings were used to evaluate motor performance. Results of this study demonstrated that riluzole dose dependently attenuated duration and intensity of harmaline-induced tremors. Also, riluzole significantly improves time to fall, distance traveled and number of crossings in combined riluzole and harmaline treated rats. Histological analysis indicated that harmaline could cause vermis Purkinje cell (PC) loss and riluzole prevented this toxic effect. Harmaline also could increase glutamate levels in vermis and treatment with riluzole restored glutamate levels. In conclusion, riluzole has relatively protective effects on harmaline-induced tremor, probably related to its inhibitory effect on glutamatergic neurotransmission. [Copyright &y& Elsevier]

Abstract: Because hypertension related alterations occur in the properties of α1-adrenoceptor in several mammalian tissues and hypertension may impact ejaculatory function, we investigated hypertension related alterations in the functional, biochemical and molecular properties of α1-adrenoceptor in the rat seminal vesicle and vas deferens. Spontaneous seminal emission in male spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats was studied during the 3-day observation period. The characteristics of α1-adrenoceptor in the seminal vesicle and epididymal and prostatic portion of vas deferens of the two strains were determined using an isolated muscle bath, radioligand receptor binding and real-time reverse transcription-polymerase chain reaction techniques. SHRs had significantly higher serum testosterone than WKY rats. However, the daily mean number of ejaculatory plugs emitted and their dry weight in SHRs were significantly lower than those in WKY rats. Although there was no significant difference in the properties of α1-adrenoceptor in the prostatic portion of vas deferens between SHRs and WKY rats, the maximum contractile responses to phenylephrine, total α1-adrenoceptor density and expression of α1A-adrenoceptor mRNA were significantly higher in the seminal vesicle and epididymal portion of vas deferens of SHRs vs. WKY rats. Our data demonstrate the presence of hypertension related alterations in serum testosterone and in α1-adrenergic responsiveness of the rat seminal vesicle and vas deferens and suggest that ejaculatory function in SHRs does not mirror these hypertension related alterations. [Copyright &y& Elsevier]

Abstract: Exposure to organophosphorus compounds, either pesticides or chemical warfare agents such as soman or sarin, represents a major health problem. Organophosphorus poisoning may induce seizures, status epilepticus and even brain lesions if untreated. Ketamine, an antagonist of glutamatergic receptors, was recently proved to be effective in combination with atropine sulfate as an anticonvulsant and neuroprotectant in mice and guinea pigs exposed to soman. Organophosphorus exposure may also occur in conditions of contemporary heat exposure. Since both MK-801, a more potent glutamatergic antagonist than ketamine, and atropine sulfate are detrimental for thermoregulation, we evaluated the pathophysiological consequences of ketamine/atropine combinations in a hot environment. Male wistar rats were exposed to 38°C ambient temperature and treated with atropine sulfate and/or ketamine (anesthetic and subanesthetic doses). The abdominal temperature and spontaneous locomotor activity were continuously monitored using telemetry. At the end of heat exposure, blood chemistry and the mRNA expression of some specific genes in the brain were assessed. Unlike MK-801, ketamine did not induce any deleterious effect on thermoregulation in rats. Conversely, atropine sulfate led to heatstroke and depressed the heat-induced blood corticosterone increase. Furthermore, it induced a dramatic increase in Hsp70 and c-Fos mRNA levels and a decrease in IκBα mRNA expression, both suggesting brain aggression. When combined with the anesthetic dose of ketamine, some of the atropine-induced metabolic disturbances were modified. In conclusion, ketamine can be used in hot environment and may even limit some of the biological alterations induced by atropine sulfate in these conditions. [Copyright &y& Elsevier]

Abstract: Numerous data indicate that Rho kinase inhibitors, such as Fasudil, may constitute a novel therapy for cardiovascular and metabolic diseases. We evaluated long-term effects of exposure to Fasudil during late gestation (10mg/day) in male rat offspring from birth until 9 months. We also analyzed its effects in offspring from hypertensive mothers treated with a nitric oxide synthesis inhibitor (L-NAME; 50mg/day). Prenatal exposure to Fasudil did not affect birth weight, but increased body weight from postnatal day 7 (P7) to 9 months. In intrauterine growth-restricted (IUGR) fetuses exposed to L-NAME, maternal Fasudil treatment increased birth weight. At P42 and P180, rats exposed to Fasudil and L-NAME showed alterations of their food intake as well as an increased basal glycemia associated with mild glucose intolerance at 6 months which was also observed in Fasudil-exposed rats. In 9 month-old rats, exposure to Fasudil increased the daily food intake as well as hypothalamic mRNA level of the orexigenic NPY peptide without modulation of the anorexigenic POMC gene expression. Altogether, our data suggest that prenatal Fasudil exposure alleviates fetal growth in IUGR rats, but programs long-term metabolic disturbances including transient perturbations of glucose metabolism, a persistent increase of body weight gain, hyperphagia and an augmented expression of hypothalamic NPY orexigenic gene. We postulate that Fasudil treatment during perinatal periods may predispose individuals to the development of metabolic disorders. [Copyright &y& Elsevier]

Abstract: Zonisamide has been proven as an effective drug for the recovery of degenerating dopaminergic neurons in the animal models of Parkinson''s disease. However, several lines of evidence have questioned the neuroprotective capacity of zonisamide in animal models of Parkinson''s disease. Although it suppresses dopaminergic neurodegeneration in animal models, the cellular and molecular mechanisms underlying the effectiveness of zonisamide are not fully understood. The current study demonstrates the effects of zonisamide on astrocyte cultures and two 6-hydroxydopamine-induced models of Parkinson''s disease. Using primary astrocyte cultures, we showed that zonisamide up-regulated the expression of mRNA encoding mesencephalic astrocyte-derived neurotrophic factor, vascular endothelial growth factor, proliferating cell nuclear antigen, metallothionein-2, copper/zinc superoxide dismutase, and manganese superoxide dismutase. Similar responses to zonisamide were found in substantia nigra where the rats were pre-treated with 6-hydroxydopamine. Notably, pharmacological inhibition of 6-hydroxydopamine-induced toxicity by zonisamide pre-treatment was also confirmed using rat mesencephalic organotypic slice cultures of substantia nigra. In addition to this, zonisamide post-treatment also attenuated the nigral tyrosine hydroxylase-positive neuronal loss induced by 6-hydroxydopamine. Taken together, these studies demonstrate that zonisamide protected dopamine neurons in two Parkinson''s disease models through a novel mechanism, namely increasing the expression of some important astrocyte-mediated neurotrophic and anti-oxidative factors. [Copyright &y& Elsevier]

Abstract: First generation H1 histamine receptor antagonists, such as d-chlorpheniramine (d-CPA) and diphenhydramine, produce drowsiness in humans. They are currently used as over-the-counter sleep aids. However, the mechanisms underlying drowsiness induced by these H1 histamine receptor antagonists remain obscure because they produce heterogeneous receptor-independent actions. Ketotifen is a second generation H1 histamine receptor antagonist which is more permeable to the brain than newer H1 histamine receptor antagonists. Therefore, to access sleep-inducing profiles by H1 histamine receptor blocking actions, the present study compared the dose-dependent effects of diphenhydramine and ketotifen (1–40mg/kg, intraperitoneal injection at dark onset time) on daily sleep–wake patterns in rats. Ketotifen dose-dependently decreased rapid-eye-movement (REM) sleep and increased non-REM sleep by amplifying slow-wave electroencephalogram powers. Diphenhydramine at 4mg/kg transiently increased non-REM sleep and reduced REM sleep similar to the effects of ketotifen. The larger injections of diphenhydramine (10–40mg/kg), however, reduced non-REM sleep, abolished slow-wave enhancements and facilitated wakefulness. The bi-directional action of diphenhydramine on sleep is similar to our former results using d-CPA. Taken together, the arousal effects caused by over-dose administrations of the first generation H1 histamine receptor antagonists may be mediated by H1 histamine receptor-independent actions. To further examine the tolerance of ketotifen-induced sleep, 3mg/kg ketotifen was injected daily for 5days 3h before light onset time. These experiments consistently enhanced non-REM-sleep at the end of the active phase of rats, suggesting that ketotifen may function as a desirable sleep aid although the coincidental REM sleep reduction requires attention. [Copyright &y& Elsevier]

Abstract: Delayed graft function secondary to ischemia/reperfusion injury has been shown to be associated with increased rate of allograft failure following kidney transplantation. Previously, we have shown that chronic lithium pretreatment protects kidney against ischemia/reperfusion injury. In the present study we aimed to examine the effects of acute lithium administration on the renal ischemia/reperfusion injury in rat. Ischemia/reperfusion injury was induced by clamping left renal pedicle for 60min, two weeks after right nephrectomy. The mechanism of lithium-mediated renoprotection was explored by combined use of lithium and nitro-l-arginine methyl ester (L-NAME) (non-selective nitric oxide synthase inhibitor) and/or indomethacin (non-selective cyclooxygenase pathway inhibitor). Lithium-treated animals were given 40mg/kg lithium chloride intraperitoneally, 30min before ischemia. To investigate the role of nitric oxide and cyclooxygenase pathways in renoprotective effect of lithium, L-NAME and/or indomethacin were administered before lithium injection. Serum creatinine, blood urea nitrogen, and renal histology were assessed after 24h of reperfusion. Lithium preconditioning significantly reduced creatinine and blood urea nitrogen (P<0.001) and improved renal histology. Administration of L-NAME completely reversed renoprotective effect of lithium. In contrast indomethacin significantly potentiated the lithium renoprotection. Moreover, co-administration of L-NAME and indomethacin completely abolished the protective effects of lithium. The results show that a single dose of lithium significantly improves renal function following ischemia/reperfusion injury. In conclusion, the ability of lithium to enhance renal tissue tolerance against ischemia/reperfusion injury suggests a potential clinical application in the setting of kidney transplantation. However, more detailed investigations are required before any definite conclusion. [Copyright &y& Elsevier]

Abstract: Abnormalities in the regulation of the hypothalamic stress hormone corticotropin-releasing factor (CRF) are thought to play a critical role in mood disorders. Consequently, CRF receptor antagonists have been proposed as potential novel therapeutic agents of these conditions. Sleep disturbance is common in depressed patients and changed sleep–wake architecture is considered as potential predictor or surrogate marker of response to treatment. The aim of our study was to characterise the effects of oral administration of the corticotropin-releasing factor CRF1 receptor antagonist R278995/CRA0450 (3 and 10mg/kg) on sleep–wake organization and electroencephalographic (EEG) components in Sprague–Dawley rats, and to determine whether the changes observed in the sleep-EEG pattern resemble those seen with antidepressants. At 3mg/kg, R278995/CRA0450 produced minor changes in sleep behaviour, while an overall reduction in power spectra was observed during deep slow wave sleep. At 10mg/kg, R278995/CRA0450 consistently reduced rapid eye movement (REM) sleep (−75.4%) and increased the REM sleep onset latency (+67%, 92.1±4.9min for vehicle vs. 153.8±24min for R278995/CRA0450), in the absence of systematic changes in spectral EEG pattern, which are characteristic anti-depressant-like effects. These findings in rats indicate that the corticotropin-releasing factor CRF1 receptor antagonist R278995/CRA0450 is centrally active under standard conditions as it inhibits REM sleep and promotes wakefulness. The characteristic changes found in the sleep EEG model further support the hypothesis that R278995/CRA0450 could exert a non-sedative, antidepressant-like action. [Copyright &y& Elsevier]

Abstract: Our previous studies showed that the hypotensive effect of chronic ethanol in female rats is reduced by ovariectomy (OVX) rats and was restored after estrogen replacement (OVXE2). Further, in randomly cycling rats, chronic ethanol increased cardiac parasympathetic dominance and subsequently reduced myocardial contractility and blood pressure (BP). In this study, we tested the hypothesis that alterations in myocardial contractility and sympathovagal control account for the E2 exacerbation of the hemodynamic effects of ethanol. BP, myocardial contractility (+dP/dtmax), and spectral cardiovascular autonomic profiles were evaluated in radiotelemetered OVX, and OVXE2 rats receiving liquid diet with or without ethanol (5%, w/v) for 13weeks. In OVX rats, ethanol caused modest hypotension along with significant increases in +dP/dtmax during weeks 2–5. The high-frequency (IBIHF, 0.75–3Hz) and low-frequency (IBILF, 0.25–0.75Hz) bands of interbeat intervals were briefly increased and decreased, respectively, by ethanol. Compared with its effects in OVX rats, chronic treatment of OVXE2 rats with ethanol elicited significantly greater and more sustained reductions in systolic (SBP) and diastolic (DBP) blood pressures and +dP/dtmax. Altered sympathovagal balance and parasympathetic overactivity were more evident in ethanol-treated OVXE2 rats as suggested by the sustained: (i) increases in high-frequency bands of interbeat intervals (IBIHF, 0.75–3Hz), and (ii) decreases in low-frequency IBI bands (IBILF, 0.25–0.75Hz), IBILF/HF ratio and +dP/dtmax. The plasma ethanol concentration was not affected by changes in the hormonal milieu. These findings suggest that estrogen exacerbates the ethanol-evoked reductions in myocardial contractility and BP and the associated parasympathetic overactivity in female rats. [Copyright &y& Elsevier]

Abstract: Palmitoylethanolamide (PEA), a peroxisome proliferator-activated receptor-α (PPAR-α) ligand, exerts antinociceptive and anti-inflammatory effects. PEA (3 and 6nmol) was microinjected in the ventrolateral periaqueductal grey (VL PAG) of male rats and effects on nociceptive responses and ongoing and tail flick-related activities of rostral ventromedial medulla (RVM) ON and OFF cells were recorded. Intra-PAG microinjection of PEA reduced the ongoing activity of ON and OFF cells and produced an increase in the latency of the nociceptive reaction. These effects were prevented by a selective PPAR-α antagonist, GW6471 and by a large-conductance Ca2+-activated K+ channel inhibitor, charybdotoxin. Cannabinoid 1 (CB1) receptor blockade by AM251 increased the PEA-induced effect both on the ongoing activity of the ON cell and on the latency to tail flick without affecting the effect of PEA on the OFF cell. Conversely, a transient receptor potential vanilloid type 1 (TRPV1) blocker, I-RTX, had no effect on the ON cell activity and tail flick latency, whereas it blocked the PEA-induced decrease in ongoing activity of the OFF cell. PEA decreased the burst and increased the latency of tail flick-evoked onset of ON cell activity in a manner antagonised by GW6471 and charybdotoxin. AM251 and I-RTX, instead, enhanced these latter effects. In conclusion, intra-VL PAG PEA induces antinociceptive effects associated with a decrease in RVM ON and OFF cell activities. PPAR-α receptors mediate, and CB1 and TRPV1 receptors antagonise, PEA-induced effects within the PAG-RVM circuitry. [Copyright &y& Elsevier]

Abstract: The role of antidepressants in the treatment of visceral pain has not been extensively examined. Milnacipran, a serotonin/noradrenalin reuptake inhibitor, has recently been approved in the USA for fibromyalgia, a chronic pathology characterized by diffused/chronic musculoskeletal pain, and a high prevalence of irritable bowel syndrome. Here, we determined its antinociceptive efficacy in two visceral pain tests in rodents: the acetic acid-induced writhing model in mice and the butyrate/colonic distension assay in rats, a model of irritable bowel syndrome. Acute milnacipran (5–40mg/kgi.p.) significantly and dose-dependently reduced writhing (72.2±3.2 versus 17.0±4.1 writhes at 40mg/kg). Following repeated administration (40m/kgi.p. for 5days), milnacipran preserved its ability to significantly reduce writhing (76±8.3 versus 21.1±6.7 writhes). Similarly, in the butyrate model, acute milnacipran (17.5 and 35mg/kg, i.p.) significantly and dose-dependently increased cramps induction thresholds (from 45.7±5.7 to 66.3±4.8 and 75.6±2.9mm Hg, for 17.5 and 35mg/kg, respectively) and reduced the number of cramps (from 3.0±0.8 to 1.2±0.8 and 0.3±0.3 following inflation of an intra-rectal balloon. To summarise, milnacipran was efficacious in the writhing test, after acute and semi-chronic administration. This effect was confirmed after acute administration in a more specific model of colonic hypersensitivity induced by butyrate. This suggests that milnacipran has potential clinical application in the treatment of visceral pain, such as in irritable bowel syndrome, highly co-morbid with fibromyalgia. [Copyright &y& Elsevier]

Abstract: There is increased understanding that distinct GABAA receptor subtypes mediate different effects of classical benzodiazepines. Here, we aimed to define the contributions of α1-containing subtypes of the subtype-selective GABAA receptor positive allosteric modulators TPA023, ocinaplon, and NG2-73 using drug discrimination. We characterized these compounds with defined subunit preferences in rats that were trained to discriminate either the non-selective benzodiazepine chlordiazepoxide (CDP, 5.0mg/kg) or the α1-selective drug zolpidem (1.5mg/kg). In short, CDP but not zolpidem generalized to the CDP cue. In contrast, zolpidem-trained rats showed opposite effects and generalized to zolpidem but not to CDP, while the response rate reducing effects of both ligands were comparable. Moreover, TPA023, lacking efficacy at the GABAA receptor α1 subunit, occasioned dose-dependent CDP-appropriate responding but generalized only to around 10% to zolpidem. Both ocinaplon and NG2-73 completely generalized to both the CDP and zolpidem cue. Overall, our data confirm and extend the previous findings in rats that compounds that lack efficacy at α1-containing GABAA receptors generalize to CDP, whereas the opposite holds true for α1-preferential compounds, which generalize to the α1-selective positive allosteric modulator zolpidem. Also, our data support the hypothesis that subtle in vitro differences in α subunit efficacy and/or affinity may eventually have large consequences in vivo. Together, our data demonstrate a reliable in vivo method to determine the contribution of the subtype-selective mechanism(s) of action for novel and subtype-selective GABAA receptor positive allosteric modulators, suggesting that a complex activation of multiple α subunits accounts for drug discrimination between non-selective and selective GABAA receptor ligands. [Copyright &y& Elsevier]

Abstract: Anti-inflammatory effects of antidepressants have been reported in some studies, but the mechanisms underlying these effects remain unknown. Amitriptyline, a tricyclic antidepressant, is widely used in the management of psychological disorders and various types of pain, including neuropathic pain or fibromyalgia. In our previous work, we found the role of supraspinal mechanisms in the anti-inflammatory effect of amitriptyline. In the line of the indicated study, we sought to evaluate the effects of intraperitoneal (i.p.) and intracerebroventricular (i.c.v.) application of amitriptyline in the carrageenan-induced paw edema in rats in more details. Our findings confirmed that i.p. (40 and 80mg/kg) and i.c.v. (100μg/rat) injection of amitriptyline inhibited carrageenan-induced inflammation at different times. We also found that both i.p. and i.c.v. amitriptyline significantly decreased migration of polymorphonuclear (PMN) leucocytes into the site of inflammation, according to pathological evidence and the activity of myeloperoxidase (MPO). Furthermore, i.p. amitriptyline at the applied doses markedly reduced interleukin (IL)-1β and tumor necrosis factor (TNF)-α levels in the paw treated with carrageenan. Our results also showed that i.c.v. amitriptyline noticeably decreased the concentration of IL-1β in the inflamed paws. The TNF-α levels reduced in the i.c.v. group, even though these reductions were not statistically significant. These results confirmed the anti-inflammatory effects of systemic and central amitriptyline in the carrageenan-induced paw edema in rats, and demonstrated that these effects mediated mostly through the inhibition of PMN cells migration and release of IL-1β and TNF-α into the site of inflammation. [Copyright &y& Elsevier]

Abstract: 5-HT6 receptor is one of the most recently cloned serotonin receptors, and it might play important roles in Alzheimer''s disease, depression, and learning and memory disorders. Availability of only very few 5-HT6 receptor agonists, however, does not allow examining their contribution in psychopharmacological processes. Therefore, a new 5-HT6 receptor agonist, ST1936, was synthesized. ST1936 binds to human 5-HT6 receptors with good affinity (Ki =28.8nM). ST1936 also exhibited some moderate binding affinity for 5HT2B, 5HT1A, 5HT7 receptors and adrenergic α receptors. ST1936 behaved as a full 5-HT6 agonist on cloned cells and was able to increase Ca2+ concentration, phosphorylation of Fyn kinase, and regulate the activation of ERK1/2 that is a downstream target of Fyn kinase. These effects were completely antagonized by two 5-HT6 receptor antagonists, SB271046 and SB258585. The other 5-HT6 receptor agonist, WAY181187 also increased Fyn kinase activity. These results suggest that both ST1936 and WAY181187 mediate 5-HT6 receptor-dependent signal pathways, such as cAMP, Fyn and ERK1/2 kinase, as specific agonists. [Copyright &y& Elsevier]

Abstract: The endogenous opioid-like peptide, nociceptin, produces anxiolytic-like effects that are mediated via the nociceptin (NOP) receptor. Similarly, synthetic, non-peptide NOP agonists produce robust anxiolytic-like effects although these effects are limited by marked side effects. In the present studies, the effects of a novel NOP receptor agonist, SCH 655842, were examined in rodent models sensitive to anxiolytic drugs and tests measuring potential adverse affects. Oral administration of SCH 655842 produced robust, anxiolytic-like effects in three species, i.e., rat, guinea pig, and mouse. Specifically, SCH 655842 was effective in rat conditioned lick suppression (3–10mg/kg) and fear-potentiated startle (3–10mg/kg) tests, a guinea pig pup vocalization test (1–3mg/kg), as well as in mouse Geller–Seifter (30mg/kg) and marble burying (30mg/kg) tests. The anxiolytic-like effect of SCH 655842 in the conditioned lick suppression test was attenuated by the NOP antagonist, J-113397. In mice, SCH 655842 reduced locomotor activity and body temperature at doses similar to the anxiolytic-like dose and these effects were absent in NOP receptor knockout mice. In rats, SCH 655842 did not produce adverse behavioral effects up to doses of 70–100mg/kg. Pharmacokinetic studies in the rat confirmed dose-related increases in plasma and brain levels of SCH 655842 across a wide oral dose range. Taken together, SCH 655842 may represent a NOP receptor agonist with improved tolerability compared to other members of this class although further studies are necessary to establish whether this extends to higher species. [Copyright &y& Elsevier]

Abstract: The effect of brain-derived neurotrophic factor (BDNF) on activity-regulated cytoskeleton-associated protein (Arc) mRNA levels in primary neuronal cultures of rat frontal cortex was characterized pharmacologically and compared to the effect on expression of c-fos, bdnf, neuritin, cox-2 as examples of other immediate early genes. BDNF induced a very strong increase (around 100 fold) in Arc mRNA and the maximal effect seen at 25ng/ml. The effect was dose-dependent with EC50 around 1.6ng/ml. The time profile revealed a significant effect after 25min. BDNF also increased levels of c-Fos, neuritin and BDNF mRNA, but not COX-2 mRNA. The pharmacological profile of NMDA and AMPA-induced arc gene expression in frontal cortical neurons was compared to BDNF. NMDA and AMPA increased Arc mRNA but their maximal effect did not exceed 20-fold. The effect of AMPA was completely blocked by the NMDA receptor antagonist MK-801. Further, the relative amount of Arc mRNA compared to c-Fos mRNA was higher for BDNF, equal for NMDA and lower for AMPA. These results demonstrate BDNF to be a highly potent and efficient inducer of arc gene expression in vitro, emphasizing the role of this growth factor in synaptic plasticity in the frontal cortex. [Copyright &y& Elsevier]

Abstract: The melanocortin MC4 receptor plays an important role in energy metabolism, but also affects blood pressure, heart rate and erectile function. Localization of the receptors that fulfill these distinct roles is only partially known. Mapping of the melanocortin MC4 receptor has been stymied by the absence of a functional antibody. Several groups have examined mRNA expression of the melanocortin MC4 receptor in the rodent brain and transgenic approaches have also been utilized to visualize melanocortin MC4 receptor expression sites within the brain. Ligand expression and binding studies have provided additional information on the areas of the brain where this elusive receptor is functionally expressed. Finally, microinjection of melanocortin MC4 receptor ligands in specific nuclei has further served to elucidate the function of melanocortin MC4 receptors in these nuclei. These combined approaches have helped link the anatomy and function of this receptor, such as the role of paraventricular hypothalamic nucleus melanocortin MC4 receptor in the regulation of food intake. Intriguingly, however, numerous expression-sites have been identified that have not been linked to a specific receptor function such as those along the optic tract and olfactory tubercle. Further research is needed to clarify the function of the melanocortin MC4 receptor at these sites. [Copyright &y& Elsevier]

Abstract: The present study examined the roles of dopamine and D1- and D2-like dopamine receptors in ventrolateral orbital cortex (VLO)-evoked antinociception in rats with persistent inflammatory pain. Following formalin injection into the rat unilateral hindpaw pad, the effects of dopamine receptor agonist and antagonist microinjections into the VLO on nociceptive behavior were observed. Results demonstrated that VLO microinjection of the non-selective dopamine receptor agonist apomorphine (R(−)-apomorphine hydrochloride, 1.0, 2.5 and 5.0μg) depressed later-phase nociceptive behavior induced by formalin injection; this effect was attenuated by the D2-like dopamine receptor antagonist S(−)-raclopride(+)-tartrate salt (raclopride, 3.0μg), but not by the D1-like dopamine receptor antagonist R(+)-SCH-23390 hydrochloride (SCH-23390, 1.0μg). Apomorphine-induced antinociception was mimicked by microinjection of the D2-like dopamine receptor agonist (−)-quinpirole hydrochloride (2.0 and 5.0μg) into the same VLO site, and this effect was antagonized by raclopride (3.0μg). In addition, microinjection of the D1-like dopamine receptor agonist R(+)-SKF-38393 hydrochloride (5.0μg) had no effect on formalin-induced nociceptive behavior during the later phase. However, the D1-like dopamine receptor antagonist SCH-23390 (2.5, 5.0 and 10μg) depressed nociceptive behavior in a dose-dependent manner. These results suggested that dopamine mediated VLO-induced antinociception via different mechanisms in the persistent inflammatory pain model; D2-like receptors mediated dopamine-induced antinociception, while D1-like dopamine receptors exhibited tonic facilitatory action on nociceptive behavior, thereby blocking D1-like dopamine receptors could induce antinociception. [Copyright &y& Elsevier]

Abstract: Respiratory behavior expresses diverse forms of plasticity by altering breathing patterns. Failure of respiratory neuroplasticity often leads to malfunctions. Long-term facilitation (LTF), the most frequently studied model induced by episodic hypoxia to produce long-lasting enhancement of phrenic motor output, is thought to be serotonin 2A (5-HT2A) receptor-dependent. Previous studies have described 5-HT-induced prompt apnea in intact animals. However, the role of exogenous 5-HT in mediating respiratory neuroplasticity is less attended in vivo study. We hypothesized that an in vivo 5-HT challenge contributes to respiratory neuroplasticity. Here, we found that systemic bolus administration of 5-HT exerted an initial transient inhibition followed by marked facilitation, forming a biphasic pattern of phrenic nerve activity in artificially ventilated, midcervically vagotomized, and anesthetized adult rats. The facilitatory phase corresponded to the enhanced phrenic nerve activity that lasted for at least one hour after drug exposure, characterized as phrenic LTF (pLTF). The 5-HT-induced biphasic pattern and pLTF were 5-HT2A receptor-dependent and coupled to protein kinase C (PKC) activation. The initial inhibition of phrenic nerve activity was found to be nodose ganglion-associated, whereas the subsequent facilitation was carotid body-associated, establishing a peripheral inhibitory–facilitatory afferent balance. Immunoreactive expressions of 5-HT/5-HT2A receptors and phospho-PKC isoforms/PKC substrate provide morphological evidence of existence of a 5-HT/5-HT2A receptor/PKC mechanism in the nodose ganglion and the carotid body. We speculate that 5-HT challenge in vivo may contribute to respiratory neuroplasticity, to yield pLTF or augmented pLTF in animals with reduced or absent peripheral inhibitory inputs. [Copyright &y& Elsevier]

Abstract: Global ischemia after cardiac arrest, intraoperative hypoxia/hypotension, and hemorrhagic shock causes brain injury resulting in severe neurological and neurobehavioral deficits. Neurodegeneration can be prevented by local aromatase expression, and estrogen synthesis can be neuroprotective in ischemia/reperfusion. Therefore, aromatase, the enzyme that transforms androgens to estrogens, may be a potential target for the study of reperfusion injury after brain ischemia. We investigated the expression of aromatase and C/EBPβ using western blotting in rat hippocampus after transient global ischemia plus hypotension. Immunohistochemical analysis was performed for aromatase. After 10min of ischemia, aromatase and C/EBPβ expression in cytosolic extracts were observed after 10min and 24h of reperfusion. The expression of both proteins was similar in control and damaged tissues. Immunoblot analysis demonstrated that the highest aromatase expression appeared in damaged hippocampi after 1week and was gradually reduced after 2–10weeks. C/EBPβ expression increased at 1week in nuclear extracts of damaged hippocampi. The aromatase inhibitor megestrol acetate (20mg/kg/day) suppressed aromatase and nuclear C/EBPβ levels in ischemic hippocampi. Our findings indicate that ischemia as well as chronic neurodegenerative processes leads to an increase in cytoplasmic aromatase and nuclear C/EBPβ. Thus, it is possible to hypothesize an interaction between this enzyme gene and transcription factor. [Copyright &y& Elsevier]

Abstract: The present study examined the effects of sustained nicotine exposure on the cholinergic vasodilative system originating in the nucleus basalis of Meynert (NBM) and projecting to the cerebral cortex in rats. Rats received sustained subcutaneous nicotine (100μg/kg/h) for 14days. Under urethane anesthesia, the vasodilation response and acetylcholine release in the parietal cortex induced by electrical stimulation of the NBM (10–200μA) were measured. The basal level of acetylcholine release was significantly higher in nicotine-treated rats than in saline-treated control rats. In the control rats, both the acetylcholine release and blood flow were increased by NBM stimulation in a stimulus intensity-dependent manner, and a threshold of 50μA. In nicotine-treated rats, the threshold intensity of NBM stimulation producing increases in acetylcholine release and blood flow was reduced to 20μA. The stimulus intensity-dependent acetylcholine release and vasodilation by NBM stimulation were significantly larger in nicotine-treated rats than in control rats. We conclude that sustained subcutaneous infusion of nicotine enhances cholinergic vasodilative system in the cerebral cortex originating in the NBM. [Copyright &y& Elsevier]

Abstract: One of the main goals of treatment of diabetes mellitus is to prevent its complications. Oxidative stress is universal in diabetes, being ultimately involved with the development complications. As a result of hyperglycemia, reactive oxygen/nitrogen species are produced in various tissues that leads to tissue damage with lipid peroxidation and protein oxidation, along with disruption in cellular homeostasis and accumulation of damaged molecules. Hence, supplementation with antioxidant compounds may offer some protection against diabetic complications. The pleiotropic effects of statins, including antioxidant and anti-inflammatory properties, represent an area of great interest in prevention and therapy of cardiovascular and neurological disorders. Using biomarkers of oxidative stress, in this study we examined the effect of non cholesterol lowering dose, long term fluvastatin treatment on oxidative stress in streptozotocin-diabetic rats. Experiments were conducted in 24 Wistar adult male rats. Diabetic and non-diabetic rats were treated orally for 6months with fluvastatin (2mg/kg/day, p.o) starting one week after streptozotocin injection (55mg/kg, i.p.), (preventive study). In brain, heart, liver, pancreas and kidney homogenates malondialdehyde, lipid hydroperoxide, protein carbonyl content, advanced oxidation protein products, 3-nitrotyrosine levels and superoxide dismutase, catalase activities were measured. Hyperglycemia and dyslipidemia in diabetic groups remained unchanged after fluvastatin treatment. The drug act as antioxidant in the tissues. Hence, antioxidant property of fluvastatin, independent of cholesterol lowering effect, may play a role in prevention of diabetic complications. Clinical relevance of this effect of fluvastatin seems worthy of further studies. [ABSTRACT FROM AUTHOR]

Abstract: Cognitive impairments have been proposed as a core feature of schizophrenia. Studies have shown that chronic or subchronic treatment with N-methyl-d-aspartate (NMDA) antagonists could induce cognitive deficits that resemble the symptoms of schizophrenia, yet few studies have investigated the effects of repeated NMDA blockade during adolescence on cognition. In the current study, adolescent, male rats were treated with an intraperitoneal injection of MK-801 (0.05, 0.1, and 0.2mg/kg) once daily for 14days. They were then tested 24h and 14days after drug cessation, respectively, in a series of behavioural tasks, including the object recognition task, the object-in-context recognition task and the working memory task of the Morris water maze (MWM). Results showed that object-in-context recognition and spatial working memory in the MWM were significantly impaired by repeated MK-801 treatment when animals were tested 24h after drug cessation, but object recognition was left intact. In particular, such deficits were observed 14days after drug cessation in the 0.2mg/kg group. The cognition-impairing effect of MK-801 could not be attributed to malnutrition or alterations in motor functions. Taken together, this study may provide support for establishing an animal model of cognitive deficits of schizophrenia based on low-dose, repeated treatment of MK-801 during adolescence. [ABSTRACT FROM AUTHOR]

Abstract: Metyrapone is a glucocorticoid synthesis inhibitor largely used to study glucocorticoid involvement in stress and memory processes. Metyrapone also acts as a stressor and therefore might modify sleep/wake patterns. However, its effects on rat sleep are unknown. We equipped 8 rats for telemetric assessment of EEG and EMG. They received first a saline injection and 2days later a 150mg/kg metyrapone injection. Metyrapone provoked immediately a waking effect together with a 3-h decrease in slow-wave sleep (SWS) and a 5-h decrease in rapid eye movement sleep (REM sleep). Thereafter, the rats exhibited homeostatic compensation through SWS and REM sleep rebounds recovering totally the sleep debt. The finding that metyrapone modified sleep patterns is important to consider for stress and memory studies using metyrapone. [ABSTRACT FROM AUTHOR]

Abstract: Nicotine has been definitively shown to be critically involved in the neural bases of tobacco addiction. However, nicotine releases a wide variety of neurotransmitters. Nicotine-induced dopamine release has been shown to play a key role in facilitating nicotine self-administration. Other transmitter systems may also play important roles in the pharmacological effects of nicotine and may provide important leads for combating nicotine self-administration. Clozapine, an antipsychotic drug, which blocks a variety of different transmitter receptors including serotonin 5HT2 and histamine H1 receptors, has been found to decrease smoking. Previously we found that the serotonin 5HT2 antagonist, ketanserin, significantly reduced nicotine self-administration. In the current study, we assessed histamine H1 receptor interaction with nicotine self-administration. Young adult female Sprague–Dawley rats were fitted with IV catheters and trained to self-administer nicotine (0.03mg/kg/infusion). Acute doses of 40mg/kg of pyrilamine, a histamine H1 antagonist, significantly reduced nicotine self-administration. We also found that repeated injections (20mg/kg) or chronic infusion via osmotic minipumps (50mg/kg/day) of pyrilamine also significantly decreased nicotine self-administration. The peripherally restricted H1 antagonist ebastine was ineffective in reducing nicotine self-administration, pointing to central H1 receptor blockade as key for the effectiveness of pyrilamine. H1 antagonists may be a promising avenue to explore for new treatments to aid smoking cessation. [ABSTRACT FROM AUTHOR]

Abstract: Co-administration of caffeine profoundly enhances the acute toxicity of 3,4 methylenedioxymethamphetamine (MDMA) in rats. The aim of this study was to determine the ability of caffeine to impact upon MDMA-induced dopamine release in superfused brain tissue slices as a contributing factor to this drug interaction. MDMA (100 and 300μM) induced a dose-dependent increase in dopamine release in striatal and hypothalamic tissue slices preloaded with [3H] dopamine (1μM). Caffeine (100μM) also induced dopamine release in the striatum and hypothalamus, albeit to a much lesser extent than MDMA. When striatal tissue slices were superfused with MDMA (30μM) in combination with caffeine (30μM), caffeine enhanced MDMA-induced dopamine release, provoking a greater response than that obtained following either caffeine or MDMA applications alone. The synergistic effects in the striatum were not observed in hypothalamic slices. As adenosine A1 receptors are, one of the main pharmacological targets of caffeine, which are known to play an important role in the regulation of dopamine release, their role in the modulation of MDMA-induced dopamine release was investigated. 1μM 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a specific A1 antagonist, like caffeine, enhanced MDMA-induced dopamine release from striatal slices while 1μM 2,chloro-N(6)-cyclopentyladenosine (CCPA), a selective adenosine A1 receptor agonist, attenuated this. Treatment with either SCH 58261, a selective A2A receptor antagonist, or rolipram, a selective PDE-4 inhibitor, failed to reproduce a caffeine-like effect on MDMA-induced dopamine release. These results suggest that caffeine regulates MDMA-induced dopamine release in striatal tissue slices, via inhibition of adenosine A1 receptors. [ABSTRACT FROM AUTHOR]

Abstract: We studied the effects of the intra-striatal infusion of Ca2+-free medium on the intra-striatal injection of 0.5μg SKF38393-induced striatal dopamine efflux. It is discussed that the amount of extracellular, striatal dopamine seen after striatally applied SKF38393, is the overall result of the (a) release of dopamine from the alpha-methyl-para-tyrosine-sensitive and Ca2+-insensitive pool of newly synthesised dopamine, (b) release of dopamine from the reserpine-sensitive and Ca2+-sensitive storage pool, (c) inhibition of uptake of dopamine into nerve terminals and glial cells, and (d) facilitation respectively of the inhibition of uptake into blood vessels: dopamine D1-like receptors play only a very limited role in these processes. The present study underlines our previous notion that the effects of SKF38393 cannot simply be ascribed to the dopamine D1-like receptor stimulation (Saigusa et al., 2009): in fact, the present study clearly reveals that SKF38393 is not at all selective in that respect. [ABSTRACT FROM AUTHOR]

Abstract: Intrathecal or epidural administration of NMDA (N-methyl-d-aspartate) receptors antagonists, in special ketamine and ifenprodil are used to control moderate to severe hyperalgesia in humans. Activation of NMDA receptor usually requires binding of two agonists, glutamate and glycine, in different receptor subunits. Ketamine is a NMDA receptor antagonist and acts at phencyclidine site in NR1 subunit while ifenprodil is a selective NR2B subunit antagonist of NMDA receptor. The aim of this study was to investigate the pharmacological interactions between ketamine or its isomers and ifenprodil, when intrathecally co-administrated, to reduce prostaglandin E2-induced hyperalgesia in rat''s hind paw. The intrathecal administration of ketamine, its isomers R(−) or S(+), or ifenprodil-induced anti-hyperalgesic effects in a dose-related manner. Ifenprodil, in a dose that did not induce significant effect when administrated alone, significantly improved the anti-hyperalgesic effect of ketamine or its isomers. The other way round, ketamine or S(+) ketamine, but not R(−) ketamine, in a dose that did not induce significant effect when administrated alone, improved the anti-hyperalgesic effect of ifenprodil. However, by comparing ED50s (half maximal effective doses), ifenprodil-induced potentiation of ketamine was significantly greater than ketamine-induced potentiation of ifenprodil. The findings of this present study suggest that intrathecal administration of very small doses of ifenprodil, just before and ketamine significantly improves its anti-hyperalgesic effect and this association could be useful to control inflammatory pain with less undesirable effects. [Copyright &y& Elsevier]

Abstract: Ischemia/reperfusion injury is a major problem in renal transplantation. Several evidences represent lithium preconditioning effect against ischemia/reperfusion injury in various tissues. In this study our aim was to investigate the protective effect of chronic lithium administration on renal ischemia/reperfusion injury in rats. Ischemia/reperfusion injury was induced by clamping left renal pedicle for 60min, 2weeks after right nephrectomy. Lithium-treated animals received lithium-chloride in drinking water for 30days. In order to investigate the role of nitric oxide (NO) and cyclooxygenase (COX) pathways in renoprotective effect of lithium, N ω-nitro-L-arginine methyl ester hydrochloride (L-NAME, NO synthase inhibitor) and indomethacin (COX inhibitor) were used, respectively. Serum creatinine, blood urea nitrogen and renal histology were assessed 24h after inducing ischemia/reperfusion injury. Dimercaptosuccinic acid scan was also performed 48h following operation. Chronic lithium treatment in ischemia/reperfusion injury groups significantly decreased creatinine (1.09±0.16mg/dl), blood urea nitrogen (59.0±13.38mg/dl), histological damage (7.83%±4.02%) and improved cortical function compared with non-lithium treated animals (4.45±0.44, 176.66±12.24mg/dl and 83.5%±3.5%, respectively) (P<0.001). Either L-NAME or indomethacin administration partially reversed the protective effect of lithium, while simultaneous blockade of NO and COX pathways completely abolished lithium renoprotective effect. Our results indicate that lithium ameliorates renal ischemia/reperfusion injury through NO and/or COX pathways. We propose that lithium pre-treatment as a simple and practical intervention to boost the renal viability and function after ischemia/reperfusion injury may be promising in the setting of transplantation. [ABSTRACT FROM AUTHOR]

Abstract: We evaluated celiprolol-induced vasodilatation in aorta taken from 12-week-old spontaneously hypertensive rats (SHR) and the effect of AT1 angiotensin II receptor antagonism on the vasodilatory action of celiprolol in Wistar Kyoto (WKY) rats and SHR. In WKY rats, the celiprolol-induced relaxation was greatly decreased in denuded aorta, and completely abolished in intact aorta by Nω-nitro-l-arginine methyl ester (l-NAME, 100μM). In SHR, celiprolol-induced relaxation was reduced compared to WKY rats (E max (value obtained for the highest concentration, 300μM)=39.1±3.78%, n =21 vs. 80.4±3% in WKY rats, n =10; P <0.0001). Endothelium removal or pre-treatment with l-NAME did not alter celiprolol-induced relaxation in SHR. In both strains, relaxation to celiprolol was decreased in the presence of nadolol (a β1/β2-adrenoceptor antagonist, 10μM). N-[[3-[(2S)-2-hydroxy-3-[[2-[4-[(phenylsulfonyl)amino] phenyl]ethyl]amino] propoxy]phenyl]methyl]-acetamide (L748337, a β3-adrenoceptor antagonist, 7μM) had no effect. A 12-day treatment with candesartan cilexetil (an AT1 receptor antagonist, 0.37 or 1mg/kg/day) reduced systolic blood pressure in both strains, but only improved relaxation to celiprolol in SHR, and only at the highest dose (E max =64.2±3.9%, n =10, P <0.0001 vs. SHR control). In both strains, local aortic AT1 receptor antagonism with candesartan CV11974 (100μM) had no effect. The endothelial β1/β2 relaxation induced by celiprolol was therefore impaired in SHR aorta and AT1 receptor antagonism improved the response to celiprolol, in conjunction with a reduction in blood pressure. This work highlights the need to analyse the potential benefit of a combination of celiprolol/AT1 receptor antagonist in the treatment of hypertension. [Copyright &y& Elsevier]

Abstract: The aim of our study was to find the most effective xylidine derivative, which reduced mortality, reduced incidence and duration of severe arrhythmias and had a beneficial influence on hemodynamic parameters in an in vivo setting. We compared the action of lidocaine, articaine, ropivacaine and mepivacaine in a dose 2.5 or 5mg/kg/ml/h infused from 10min before left anterior descending coronary artery occlusion until the end of the experiment. In the rat ischemia- and re-perfusion-induced arrhythmia models, the following parameters were measured or calculated: mortality index, ventricular fibrillation and tachycardia incidence and duration, systolic, diastolic and mean arterial blood pressure, heart rate and pressure rate product. Lidocaine produced the most significant reduction in mortality index (P <0.05) after both doses. At the higher dose, lidocaine and articaine shortened ventricular fibrillation and tachycardia duration (P <0.05–P <0.001), while ropivacaine prolonged them. A hypertensive effect was observed after a lower dose of lidocaine during occlusion and early re-perfusion as compared to others (P <0.05). Beneficial effects were mainly observed with lidocaine, which protected against sudden cardiac death. The novelty was lidocaine''s dose independent protection against blood pressure drop in early re-perfusion, which could be linked to the effects observed on the other end-points. Articaine showed beneficial effects but they weren''t as pronounced as that of lidocaine. Nevertheless, in the light of our results, articaine could supposedly be used as a substitute for lidocaine in patients with hypertension. [Copyright &y& Elsevier]

Abstract: Amphetamine use is associated with dysphoric states, including heightened anxiety, that emerge within 24h of withdrawal from the drug. Corticotropin-releasing factor increases serotonin release in the central nucleus of the amygdala, and this neurochemical circuitry may play a role in mediating fear and anxiety states. We have previously shown that chronic amphetamine treatment increases corticotropin-releasing factor receptor type-2 levels in the serotonergic dorsal raphe nucleus of the rat. Therefore, we hypothesized that chronic amphetamine treatment would enhance the amygdalar serotonergic response to corticotropin-releasing factor infused into the dorsal raphe nucleus. Male rats were injected once-daily with d-amphetamine (2.5mg/kg i.p., or saline) for two weeks. Serotonin release within the central nucleus of the amygdala in response to intra-raphe infusion of corticotropin-releasing factor (100ng) was measured 24h after the last treatment in urethane-anesthetized (1.8mg/kg, i.p.) rats using in vivo microdialysis. Rats pretreated with amphetamine showed significantly enhanced serotonin release in the central nucleus of the amygdala in response to corticotropin-releasing factor infusion when compared to saline pretreated rats. Furthermore, this enhanced response was blocked by the corticotropin-releasing factor type-2 receptor antagonist antisauvagine-30 (2μg) infused into the dorsal raphe nucleus. These results suggest increased sensitivity to corticotropin-releasing factor as mediated by type-2 receptors following chronic amphetamine treatment, which may underlie dysphoric states observed during amphetamine withdrawal. [ABSTRACT FROM AUTHOR]

Abstract: Arvanil is a metabolically stable hybrid between anandamide and capsaicin. The present study was designed to test the role of the vagal pathway in post-arvanil respiratory and blood pressure responses. Respiratory and pressure changes evoked by an intravenous injection of arvanil were investigated in 21 urethane–chloralose anaesthetised and spontaneously breathing rats. In control neurally intact rats the effects of arvanil were checked to establish the appropriate dose of the drug. In the experimental group rats were challenged with arvanil while intact, following bilateral midcervical vagotomy and after subsequent supranodose vagotomy. In all neurally intact animals bolus injection of 0.8mg/kg of arvanil into the right femoral vein induced a significant increase of tidal volume (+1±0.11ml; P <0.01) and diaphragm activity (+1.72±0.1 arbitrary units; P <0.01) as well as hypertension (+31.9±2.9mm Hg; P <0.001) and a fall in respiratory rate (−24.7±0.4breath/min; P <0.001). Bilateral midcervical vagotomy precluded the alteration of respiratory parameters but did not eliminate blood pressure response. Arvanil-induced increase in mean arterial blood pressure still persisted after supranodose vagotomy. Results indicated that the respiratory effects evoked by arvanil administered via the peripheral circulation require intact midcervical vagi. Supranodose vagotomy failed to eliminate the hypertension evoked by arvanil. [Copyright &y& Elsevier]

Abstract: The objective of this study was to determine possible effects and potential mechanisms of cardamonin on improving insulin resistance and vascular proliferative lesions in the rat''s model system. Fed with 60% fructose-enriched diet for 12weeks, male Sprague–Dawley (SD) rats developed insulin resistance and hyperinsulinemia. They also showed excessive proliferation of the vascular smooth muscle cells (VSMCs) and activation of the mammalian target of rapamycin (mTOR)/translation control proteins p70 ribosomal S6 kinase (P70S6K1)/eukaryotic initiation factor 4E binding protein 1 (4E-BP1) signaling in the rat thoracic aorta. From weeks 9–12, cardamonin was injected into the peritoneal cavity once daily. Under the detection of microscopy and electron microscopy, cardamonin improved hyperinsulinemia and inhibited proliferation of VSMCs in the thoracic aorta of rats in a dose-dependent manner. By the Real-Time RT-PCR, mRNA expression of mTOR, P70S6K1 and 4E-BP1 was significantly reduced in cardamonin treated rats. Similarly, protein over-expression of mTOR and p-P70S6K1 was obviously inhibited by immunohistochemical analyses. These findings suggest that cardamonin may play a role in ameliorating insulin resistance and smooth muscle hyperplasia of major vessels in fructose-induced rats, possibly via a mechanism that involves the modulation of insulin/mTOR signaling. [Copyright &y& Elsevier]

Abstract: Duration of heart rate corrected QT interval (QTc) is a crucial and critical factor in the assessment of repolarization changes considering safety of drugs and cardiac disorders. In rats, a validated approach to QT correction is lacking. In this study, we tested the normalization of QTc using normalization factor according to rat''s cardiac cycle length (RR). Standard 12-lead ECG was measured in anesthetized rats at basal conditions and at various pharmacological conditions such as beta-adrenergic stimulation with isoproterenol or medication with clarithromycin (single- or repeated dosing for seven days), bisoprolol or ivabradine. For QT correction, standard Bazett''s formula (QTc-B=QT/(RR)1/2) and Bazett''s formula normalized to average rat RR (QTcn-B=QT/(RR/ f)1/2, f =150ms) were compared. Duration of QT showed a positive correlation with RR duration (Pearson r =0.7645, P <0.001). Calculated QTc-B gave 2–2.5 fold of values of uncorrected QT, whereas values of normalized QTcn-B were in the physiological range. QTcn-B was unrelated to RR (Pearson r =0.1122, not significant) but the relationship between QTcn-B and QT remained preserved (Pearson r =0.7216, P <0.001). Both single and repeated administration of clarithromycin prolonged QT as compared to the controls but a significant dose-dependent difference between clarithromycin applications was revealed only when QTcn-B was used. Beta-adrenergic stimulation with isoproterenol prolonged, while beta-blockade with bisoprolol shortened QTcn-B. Ivabradine dose-dependently induced bradycardia without altering QT. However, QTcn-B showed false positive shortening at sustained bradycardia. Therefore, adjusted formula for QTcn-B is suitable for QT correction in rats but its use should be considered carefully in case of very low heart rate. [Copyright &y& Elsevier]

Abstract: Doxorubicin is an effective anti-neoplastic agent application of which has been limited due to its cardiotoxic side effects. Lithium is widely used for treatment of neuropsychiatric symptoms in bipolar disorders. Lines of evidence point to the cardioprotective effects of lithium against heart injuries. The current study aims to investigate the protective effects of lithium against doxorubicin-induced cardiotoxicity in rat model. Male Wistar rats were treated with 300mg/kg p.o. lithium in their water supply and/or doxorubicin (1.25mg/kg, i.p.), four times per week for four weeks. General conditions, mortality rate and body weight were measured during the experiment. At the end of the experiment, ECG parameters and papillary muscle contractility force were assessed. Serum samples were collected to measure the lithium concentrations as well as cardiac troponin T level (cTNT, a biomarker of cardiac injury). In addition, heart weight was measured and the cardiac tissues were evaluated both macroscopically and microscopically. The results of the present study indicate that lithium might diminish mortality rate, general toxicity (edema, alopecia and cachexia), improve Sα–T segment and QT interval prolongations as well as heart contractility force. Application of lithium could inhibit the increase of cardiac troponin T and formation of myocardial lesions. These outcomes show the protective effects of lithium against doxorubicin-induced cardiotoxicity in rat. On the whole, the results of the present study suggest that lithium might be considered as a new indication for the prevention of doxorubicin-induced cardiotoxicity. [Copyright &y& Elsevier]

Abstract: Excessive intracellular Na+ accumulation followed by Ca2+ overload in cardiac tissue is one of the important mechanisms leading to ischemia/reperfusion injury. In the present study, the cardioprotective effects of 44Bu, 2-hydroxy-3-(butylamino) propyl-4-{(butoxycarbonyl)amino}benzoate hydrochloride, a novel Na+ channel blocker, on ischemia/reperfusion injury were investigated and compared to lidocaine. Isolated rat hearts perfused at the constant flow were exposed to global ischemia for 60min followed by 30min of reperfusion. In control hearts, ischemia/reperfusion markedly decreased left ventricular developed pressure and increased left ventricular end-diastolic pressure, and caused lactate dehydrogenase release and infarction. 44Bu (0.1, 0.3 and 1µM) or lidocaine (1 and 200µM) was administrated during the last 10min before ischemia and the first 5min of the reperfusion period. A significant post-ischemic functional recovery in the same degree was elicited by 0.3 and 1μM 44Bu or 200µM lidocaine. These effects of 44Bu and lidocaine closely correlated with the reduction in the infarct size and lactate dehydrogenase release. In contrast, 44Bu (0.1µM) or lidocaine (1µM) treatment did not result in a significant recovery in any of the examined parameters. In accordance with functional results, our electrophysiological data demonstrated that 44Bu was a more potent agent than lidocaine in terms of transient Na+ current inhibition. On the other hand, 44Bu did not cause any change in Ca2+ currents and on Na+/H+ exchange activity. These results show that 44Bu, as a novel Na+ channel blocker, has cardioprotective effects against ischemia/reperfusion injury. [Copyright &y& Elsevier]

Abstract: We recently identified 6-(4-methoxyphenyl)-5-methyl-3-pyridin-4-ylisoxazolo[4,5-c]pyridin-4(5H)-one (MMPIP), the first allosteric metabotropic glutamate (mGlu) 7 receptor-selective negative allosteric modulator. In this study, we examined the in vivo pharmacological effects of MMPIP on the central nervous system. MMPIP was distributed into the brain after systemic administration in both mice and rats. Pharmacokinetic study revealed that the half-life of MMPIP in circulation was about 1h in rats. Results of various behavioral studies revealed that MMPIP impaired non-spatial and spatial cognitive performances in the object recognition test and the object location test in mice, respectively. In rats, MMPIP increased time to complete the task in the 8-arm radial maze test without increasing error. In addition to impairing cognition, MMPIP decreased social interaction with reduction of line crossing in rats, while MMPIP had no effects on locomotor activity in rats and mice, rota-rod performance in mice, prepulse inhibition in rats, maternal separation-induced ultrasonic vocalization in rat pups, stress-induced hyperthermia in mice, or the tail suspension test in mice. No analgesic effects of MMPIP were detected in either the tail immersion test or formalin test in mice. MMPIP did not alter the threshold for induction of seizures by electrical shock or pentylenetetrazole in mice. These findings suggest that blockade of mGlu7 receptors by MMPIP may modulate both non-spatial and spatial cognitive functions without non-selective inhibitory effects on the central nervous system. [Copyright &y& Elsevier]

Abstract: The role of the metabotropic glutamate receptor 5 (mGlu5 receptor) in learning and memory and other behaviors are reviewed by examining the influence of selective antagonists and genetic knockout on performance. This receptor is involved in spatial learning, contextual fear conditioning, inhibitory avoidance, fear potentiated startle, and conditioned taste aversion. However, mGlu5 receptor antagonists have proven to be ineffective in other learning tasks, such as the delayed-match-to-position test and a three-hole spatial learning task. Locomotion is often decreased by mGlu5 receptor antagonists; and other behaviors such as social interaction and consummatory responses can also be affected. In mGlu5 receptor knockout mice, performance in contextual fear conditioning and spatial water maze tasks is impaired. Although the available evidence is suggestive of an important contribution of mGlu5 receptors to cognitive functions, further studies are needed, particularly those with in vivo evaluation of the role of mGlu5 receptors in selective brain regions in different stages of memory formation. [Copyright &y& Elsevier]

Abstract: Previously, it was shown that intravenous (i.v.) treatment with the essential oil of Aniba canelilla (EOAC) elicited a hypotensive response that is due to active vascular relaxation rather than to the withdrawal of sympathetic tone. The present study investigated mechanisms underlying the cardiovascular responses to 1-nitro-2-phenylethane, the main constituent of the EOAC. In pentobarbital-anesthetized normotensive rats, 1-nitro-2-phenylethane (1–10mg/kg, i.v.) elicited dose-dependent hypotensive and bradycardiac effects which were characterized in two periods (phases 1 and 2). The first rapid component (phase 1) evoked by 1-nitro-2-phenylethane (10mg/kg) was fully abolished by bilateral vagotomy, perineural treatment of both cervical vagus nerves with capsaicin (250µg/ml) and was absent after left ventricle injection. However, pretreatment with capsazepine (1mg/kg, i.v.) or ondansetron (30µg/kg, i.v.) did not alter phase 1 of the cardiovascular responses to 1-nitro-2-phenylethane (10mg/kg, i.v.). In conscious rats, 1-nitro-2-phenylethane (1–10mg/kg, i.v.) evoked rapid hypotensive and bradycardiac (phase 1) effects that were fully abolished by methylatropine (1mg/kg, i.v.). It is concluded that 1-nitro-2-phenylethane induces a vago-vagal bradycardiac and depressor reflex (phase 1) that apparently results from the stimulation of vagal pulmonary rather than cardiac C-fiber afferents. The transduction mechanism of the 1-nitro-2-phenylethane excitation of C-fiber endings is not fully understood and does not appear to involve activation of either Vanilloid TPRV1 or 5-HT3 receptors. The phase 2 hypotensive response to 1-nitro-2-phenylethane seems to result, at least in part, from a direct vasodilatory effect since 1-nitro-2-phenylethane (1–300µg/ml) induced a concentration-dependent reduction of phenylephrine-induced contraction in rat endothelium-containing aorta preparations. [Copyright &y& Elsevier]

Abstract: The level of mRNA encoding calcyon (measured by in situ hybridization), one of the dopamine receptor interacting proteins, has been examined in the rat brain in the established animal model used to study the mechanisms of cocaine addiction (cocaine self-administration involving a yoked procedure). Two weeks of cocaine self-administration (maintenance) did not affect the level of calcyon mRNA, regardless of the way cocaine was delivered, except for tuberculum olfactorium, where calcyon mRNA was increased after cocaine treatment. In the reinstatement phase of the experiment cocaine alone induced an increase in the calcyon mRNA expression in most of the brain region studied (caudate putamen; tuberculum olfactorium; paraventricular thalamic nucleus; ventromedial hypothalamic nucleus and paraventricular hypothalamic nucleus) but only in the yoked saline control group. In other words, these results show that the single dose of cocaine (10mg/kg) was able to induce an alteration in the level of calcyon mRNA in these rats which never before experienced any cocaine administration. The most significant effects were observed in the ventromedial hypothalamic nucleus and paraventricular hypothalamic nucleus. Interestingly, a similar effect was observed when the reinstatement of cocaine-seeking behaviour was evoked by cue (conditioned stimuli) that indicates that no cocaine was necessary to induce the changes in the level of calcyon mRNA expression. This effect was significant in tuberculum olfactorium, ventromedial hypothalamic nucleus and paraventricular hypothalamic nucleus. Such a result together with the brain areas involved in these effects might suggest the role of calcyon similar to the CART peptides and special vulnerability of calcyon expression rather to acute than chronic stimuli. [Copyright &y& Elsevier]